Influence of position variation of selenium atom and electron‐withdrawing substituents on charge transport, opto‐electronic, photovoltaic, chemical reactivity indices, and thermodynamic properties of pentatetraselenophene molecules

Abstract In this research, we have studied the effect of variation in the position of the selenium atom and substitution of different electron‐withdrawing groups (─Cl, ─CN, ─COCl) in pentatetraselenophene (PTSe) molecule on their charge transport, electronic, optical, photovoltaic, chemical reactivity indices, and thermodynamic properties. All the calculations of this study were performed by employing the density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) at B3LYP functional and 6–31(d,p) basis set in the gaseous state. Additionally, the density of states calculation was performed with the help of Gauss Sum software by using the DFT‐optimized structures. The results of optoelectronic properties demonstrate that the absorption wavelengths and energy gaps ( E g ) of all the investigated compounds range from 457 to 689 nm and 2.131 to 2.335 eV. In comparison, all PTSe‐based compounds had lower hole/electron reorganization energies (86–161 meV/94–202 meV) than typical materials (less than 290/276 meV), indicating that they transport electrons and holes more efficiently. Instead, all PTSe‐based compounds can be utilized as hole‐carrying materials because the hole reorganization energy is lower than the electron reorganization energies. Moreover, the difference between the hole and electron reorganization energies is less (about 3–25 meV), which means most of the examined molecules (except PSe7 ) can be employed as ambipolar charge‐transport materials. The predicted open circuit voltages of the examined compounds range from 0.975–2.179 eV, which are adequate for effective electron injection. This work highlights that the substitution of electron‐withdrawing groups and the alteration in the position of the selenium atom can be a prominent material for charge transport and ambipolar organic semiconductors. Our study serves as a supportive way for further designing and fabrication of a new type of organic semiconductor material for applications in photovoltaic solar cells, OLEDs, and OFETs.